Angle-of-attack

Abstract

To provide an angle-of-attack control device of a vertical axis windmill capable of operating the angle of attack of a rotary blade in the vertical axis windmill by the direction of blowing wind and wind power without power and without operation from the outside.SOLUTION: A support shaft 3 which is parallel to the chord of a rotary blade and faces slightly upward is provided at the upper end of the rotary blade 2, and a vertically long fin-like member 4 which is rotatable and normally faces upward is attached to the support shaft. A spring 6 having a neutral point upward is attached to the fin-like member. The spring is a wire spring freely bendable in each direction, and has an intermediate support member 7 movable in the span direction of the rotary blade and from the inside to the outside of the rotation circumference at an intermediate point.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a device for utilizing wind energy, and in particular to a device for controlling the angle of attack of the rotor blades within an appropriate range relative to the wind direction in a wind turbine whose rotation axis is set approximately perpendicular to the wind direction and whose rotor blade span is approximately parallel to the rotation axis. [Background technology]

[0002] Wind turbines currently in practical use can be broadly divided into two types: horizontal axis and vertical axis. The former is a so-called propeller type consisting of a rotating shaft extending horizontally and a propeller attached to it, while the latter is composed of a rotating shaft in a nearly vertical direction and multiple rotors extending nearly parallel to the rotating shaft. This invention relates to the latter type, and aims to improve the performance of such wind turbines.

[0003] Vertical axis wind turbines are generally used as a means of providing inexpensive products due to their simple structure, and there has not been sufficient research aimed at improving their performance and practicality. As a result, existing turbines still lack the essential characteristics of starting and output control. The main reason for this is that the wings are fixedly attached to the mounting arms, so that the angle of attack relative to the wind is not correct during operation, resulting in a stall in most cases. The mechanism for properly controlling this angle of attack is not simple, and no effective mechanism has been found other than the patents pending by the applicant of this application. The present invention is effective in addition to these applications, and addresses this from an aerodynamic perspective, providing a simple mechanism unit that dramatically improves the performance of vertical axis wind turbines. In order for a vertical axis wind turbine to perform at its full potential, it is important that the rotor blades that rotate when exposed to the wind maintain an appropriate angle of attack relative to the relative airflow caused by the wind and its rotational motion. To achieve this, the blades must be rotatably attached to the attachment arms and must rotate periodically according to the rotation angle and position relative to the wind direction. Furthermore, sudden changes in wind direction are expected, and a control function that can respond to these changes without delay is required, but achieving this smoothly is quite difficult. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application No. 2021-203765, filed by the applicant, is based on a mechanism that periodically controls the angle of attack of multiple blades through the three-dimensional swinging motion of a swing plate. While functionally it is necessary and sufficient, it has drawbacks, such as a somewhat complicated structure and the difficulty of adjusting the multiple rotor blades to the optimal state. [Patent Document 2] Japanese Patent Application No. 2024-006349, also filed by the applicant, aims to provide a so-called windsock effect to the entire wing by placing the rotor shaft further forward than the leading edge of the wing and providing a fin-shaped stabilizer further rearward than the trailing edge. While there is no difficulty in adjustment like in the previous application, there is a concern that the presence of a fin behind the rotor shaft may cause delays in operation during rotation. Summary of the Invention

[0005] The present invention relates to a rotor angle-of-attachment control device that enables the rotor to maintain an appropriate angle of attack with a simple configuration that includes a fin member that extends upward and is rotatable about a rotation axis that is parallel to the chord of the rotor and tilted slightly upward, near the tip of the rotor that is rotatably attached to an arm, and a neutral spring that holds the fin member in position. This can improve the difficulty of adjustment as in Patent Document 1 and the concern about operational delays as in Patent Document 2. A support shaft is provided at the tip of a rotor that is long in the span direction and is rotatable around a rotation shaft in the span direction near the tip of the arm-like member, and is parallel to the chord of the rotor and faces slightly upward. A vertically long fin-like member that faces upward and is rotatable is attached to the support shaft. A spring with a neutral point at the top is attached to the fin-like member. The spring is preferably a wire spring that can bend freely in any direction, and preferably has a movable intermediate support member at the midpoint. In this state, when wind strikes the blade from diagonally forward of the chord, the fin-shaped member rotates around the support shaft, causing it to flap downwind and twist in the direction of the wind, increasing the angle of attack of the fin-shaped member itself. The reaction force acting on the fin member against the wind, which generates an angle of attack, becomes a rotational force that reduces the angle of attack of the rotor. This rotational force causes the rotor arm to rotate. If the wind direction becomes head-on with respect to the rotor, this movement of the fin-shaped member will cease and it will return to its neutral point. If the wind angle of attack relative to the rotor reverses, the fin-shaped member's flap angle will also reverse, resulting in the opposite movement. As a result, the rotor's angle of attack will tend to remain at the neutral point. The appropriate angle of attack for obtaining the rotational force required by the rotational resistance applied to the rotor from the outside is determined by the degree to which the fin-shaped member bends due to the flexibility of the spring having the neutral point. As described above, the angle-of-attack control device of the present invention provides an excellent technology that can achieve the required functions with an extremely simple structure. By moving the intermediate support member that supports the middle part of the spring from the outside in the span direction of the rotor, it is possible to adjust the ductility with which the spring supports the fin member. In addition, by moving it inward or outward of the rotor's rotation circle, it is possible to fine-tune the angle of attack of the rotor. [Problem to be solved by the invention]

[0006] The problem to be solved by this invention is to realize reliable and smooth control of the angle of attack in a vertical axis wind turbine with an extremely simple mechanism, thereby dramatically improving its performance, reducing costs, and greatly expanding its practicality. [Means for solving the problem]

[0007] The means for solving the above problems of the present invention is to provide a support shaft that is parallel to the chord of the rotor and points slightly upward at the tip of the rotor, which is long in the span direction and is attached to the tip of an arm-shaped member that rotates around the rotation axis of the wind turbine itself, and is rotatable around a rotation axis in the rotor span direction, and a vertically long fin-shaped member that points upward is attached to the support shaft and is rotatable around the rotation axis in the rotor span direction. A spring with a neutral point at the top is attached to the fin-shaped member. The spring is preferably a wire spring that can bend freely in all directions, and preferably has an intermediate support member at its midpoint that can move in the span direction of the rotor blade and inward or outward of the rotation circumference. Assume that the wind (horizontal airflow) strikes the rotors and fins when the wind turbine is stopped. Focusing on the rotor that receives the wind from the diagonal leading edge, the fin attached to the upper end rotates around a support shaft facing diagonally upward, causing it to bend downwind and twist so that the angle of attack of the fin itself increases relative to the wind direction. The reaction force against the wind generated by this angle of attack acts as a rotational force that reduces the angle of attack of the rotor. This rotational force causes the rotor to rotate relative to the arm, rotating so that the leading edge of the rotor faces upwind and the trailing edge faces downwind. This rotation brings the angle of attack of the rotor within the appropriate range (approximately ±10°). This generates lift on the rotor, and the circumferential component of this lift relative to the rotation of the wind turbine becomes a rotational force, starting the wind turbine. When the other rotors of the wind turbine rotate to the above position, they start up in a similar manner, and the wind turbine goes into continuous rotation. If there are two or more rotors, it is possible to transition from starting motion to steady rotation, but three or more are preferable. When the wind direction is from the front of the rotor, the fin-like members stop flapping and return to the neutral point. When the wind angle of attack with the rotor is reversed, the fin-like members also reverse their flapping angle, resulting in the reverse of the motion described above. The cross-sectional shape of the rotor does not have to be vertically symmetrical, but can be specially curved. As a result, the angle of attack of the rotor blades tends to be maintained at the neutral point. However, the appropriate angle of attack required to obtain the required rotational force due to the rotational resistance applied to the rotor blades from the outside depends on the degree to which the fin-shaped members bend due to the stiffness of the springs with the neutral point. This action is a continuous series of actions, and no discontinuities occur. The angle of bend can be easily adjusted by externally moving the intermediate support members in the rotor blade span direction. Each rotor blade moves independently, and adjustments can be made individually, but it is desirable to adjust the stiffness of this spring to a uniform value. The angle of attack of the rotor blades can also be fine-tuned by moving the intermediate support members inward or outward of the rotor blade rotation circle. However, these adjustments only need to be made during initial setup depending on the wind turbine's application. [Effects of the Invention]

[0008] The effect of the angle of attack control device having the above structure is that it can properly control the angle of attack of the rotors using the force of the blowing wind (air current) itself, without requiring any external control force or control operation, which is completely different from current yachts, sailing ships, horizontal axis wind turbines, etc. It is a fully automatic, non-powered control mechanism, and the operation of each rotor is independent rather than linked, which allows for a significant structural simplification and cost reduction. The effect is to reduce the stress and vibration of the wind turbine and supporting equipment caused by an inappropriate angle of attack of the rotors, thereby making it possible to reduce the size and weight, promoting the expansion of use from fixed wind turbines to mobile wind turbines, and dramatically improving their response characteristics to changing conditions, and its industrial effect is extremely significant. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a front view showing an embodiment of the present invention. [Figure 2] FIG. 2 is a top view showing one embodiment of the present invention. [Figure 3] FIG. 3 is a side view showing one embodiment of the present invention. [Figure 4] FIG. 4 is a partial front view showing another state of the embodiment of the present invention. [Figure 5] FIG. 5 is a partial top view showing another state of one embodiment of the present invention. [Figure 6] FIG. 6 is a partial side view showing another state of the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment will be described in which the attack angle control device of the present invention is simplified to the extent that its function is not impaired. [Example]

[0011] In Figures 1 to 6, this relates to a device that can maintain an appropriate angle of attack with a simple configuration consisting of: arm member 1 attached to the rotation shaft of a wind turbine, arm member 1 is rotatably attached to an axis parallel to the rotation shaft of the wind turbine near the tip of arm member 1; rotor blade 2 whose span direction is parallel to the rotation shaft; support shaft 3 that is inclined upward and parallel to the chord direction of rotor blade 2 near the tip of arm member 1; fin-shaped member 4 rotatably attached to support shaft 3; and spring 6 with neutral point 5. The spring 6 is preferably a wire spring that can bend freely in all directions, and preferably has an intermediate support member 7 at its midpoint that can move in the span direction of the rotor blade and inward or outward of the rotation circumference. 4 and 5, we consider a situation in which wind (horizontal airflow) strikes the rotor 2 and fin member 4 when the wind turbine is stopped. Focusing on the rotor 2 that receives wind W from the diagonally leading edge of the multiple rotors 2, the fin member 4 attached to the upper end rotates around the support shaft 3 facing diagonally upward, causing it to bend downwind (indicated by arrow A) and twisting so that the angle of attack of the fin member 4 itself increases relative to the wind direction. The reaction force against the wind generated by this angle of attack acts as a rotational force that reduces the angle of attack of the rotor 2. This rotational force causes the rotor 2 to rotate in the direction of arrow B relative to the arm member 1, causing the rotor 2 to rotate in a direction such that the leading edge of the rotor 2 faces upwind and the trailing edge faces downwind. This rotation brings the angle of attack of the rotor 2 within the appropriate range (approximately ±10°). This generates lift on this rotor 2, and the circumferential component of this lift relative to the rotation of the wind turbine becomes a rotational force, starting the wind turbine. When the other rotors 2 of the wind turbine rotate to the position described above, they start due to a similar phenomenon, and the wind turbine enters a state of continuous rotation. If there are two or more rotors 2, it is possible to transition from starting motion to steady rotation, but three or more are preferable. If the wind direction is from the front of the rotor 2, the flapping motion of the fin-like members 4 will cease and they will return to the neutral point. If the angle of attack of the wind relative to the rotor 2 is reversed, the flapping angle of the fin-like members 4 will also be reversed, resulting in the reverse motion of the above. As a result, the angle of attack of the rotor 2 tends to be maintained at the neutral point, but the appropriate angle of attack to obtain the required rotational force due to the rotational resistance applied to the rotor 2 from the outside is determined by the degree to which the fin-shaped member 4 bends due to the flexibility of the spring 6, which has the neutral point. This operation is a continuous series of operations, and no discontinuities occur. The angle of bend of the fin-shaped member 4 can be easily adjusted by externally moving the intermediate support member 7 in the span direction of the rotor 2. In addition, the angle of attack of the rotor can be fine-tuned by moving the intermediate support member 7 inward or outward of the rotor's rotation circle. The movement of each rotor 2 is independent and adjustments can be made individually, but it is desirable to adjust the stiffness of this spring 6 to a uniform value. However, this only needs to be done at the time of initial setup depending on the application of the wind turbine. (action)

[0012] The operation of the angle-of-attack control device of the present invention having the above-described structure will now be described. The above series of actions of the rotor 2 and fin-like members 4 are not performed by external operation or external force, but are entirely dependent on the direction and force of the wind, and are performed fully automatically without power. This is an extremely important function for a wind turbine that rotates in natural wind. Also, because there is no stall in the rotors, the resistance of the entire turbine in the downwind direction is very small. Therefore, it is not only used as a power plant, but also as a propulsion source that can move forward regardless of wind direction.

[0013] The angle of attack control device of the present invention is a non-powered, fully automatic device that operates only by the force of the wind. As a device that utilizes natural energy, the industrial effect is extremely significant. [Explanation of symbols]

[0014] 1 Arm-shaped member 2 rotor blades 3 Support shaft 4 Fin-shaped member 5 Neutral point 6 Spring 7 Intermediate support member

Claims

1. This angle-of-attack control device has a structure in which a support shaft is provided at the upper end of a rotor that is parallel to the rotation axis and is elongated in the span direction and parallel to the rotation axis, and a rotatable, vertically elongated fin-shaped member that is normally upwardly facing is attached to the support shaft, and a spring with a neutral point at the top is attached to the fin-shaped member.

2. 2. An angle-of-attack control device according to claim 1, wherein an intermediate support member of the spring having a neutral point is configured to be movable in the span direction of the rotor blade and to the inside or outside of the rotation circumference of the rotor blade.

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